With so many technological advancements, why has there been no direct mechanical or chemical brain enhancement

With surveys indicating that people are feeling more and more disillusioned and cynical towards life, and with people committing suicide, clearly there is room for improvement. Can't human efforts be made to enhance the brain in such a way that we are more motivated, happy, and connected with the world? To those that say the brain is too complex to be messed around with, wouldn't that complexity prove that we are capable of enhancing the brain at a chemical, biological and/or mechanical level?